Step 10: Use the top arc as a guide to draw the spinosaurus' upper jaw. Follow the path of the guide and make the shape bumpier as you darken the line. The line that makes up the mouth stretches to the left and inside the circle. Draw a series of small, triangle-like shapes that line the mouth for the teeth. The spinosaurus was mainly a fish-eater and had a crocodilian skull, so space the teeth apart and make them different sizes. Draw a few lines in between the teeth to indicate some indentation.

Step 11: Use the arc on the bottom as a guide to draw the spinosaurus' lower jaw. Draw a few lines to show the tissue that connects the jaw. Lightly sketch out the shape of the lower jaw by following the path of the guide but making it thinner and curvier. Add the dinosaur's teeth as small, triangle-like shapes across the mouth. Make them different sizes and space them out. Darken the shape of the spinosaurus' jaw and make it wider on the left. Draw a line inside the mouth for the tongue.

Step 12: Use the initial circle shape as a guide to draw the rest of the spinosaurus' head. Draw a series of curved lines on the left side.

Step 13: Using the lines on the right as guides, draw the spinosaurus' arms. Sketch lightly at first as you follow the basic path of the guides. Use curved lines to indicate the muscles in the arms and add the digits at the end. Darken the lines when you get the structure of the dinosaur's first arm right. Draw the claws at the end of the digits. Use the other line to draw the arm on the other side the same way. Sketch lightly as you follow the basic path of the guide lines. Darken the lines when you get the structure right. Add the digits and claws at the end.

Step 14: Use the lines on the left as guides to draw the spinosaurus' legs. Lightly sketch the shape of the first leg as you follow the basic path of the guide. Darken the lines when you get the structure right. The top of the leg should be thicker. Use curved lines to indicate the muscle structure and joints. Draw the claws at the tip of the spinosaurus' feet. Use the other line to draw the leg on the other side the same way. Make the top of the dinosaur's leg thicker. The spinosaurus is stepping forward, so it should have a wide stride.